mek25
contestada

The difference of the square of a number and 9 is equal to 8 times that number. Find the positive solution.

Respuesta :

subtomex0

[tex]x {}^{2} - 9 = 8x \\ x {}^{2} - 8x - 9 = 0 \\ x = \frac{ - ( - 8) + \sqrt[]{( - 8) {}^{2} - 4(1)( - 9)} }{2( {1}^{}) } [/tex]

[tex]x = \frac{8 + \sqrt{64 + 36} }{2} = \frac{8 + \sqrt{100} }{2} = \frac{8 + 10}{2} = 9[/tex]

rdacoder

Answer: x = 9

Step-by-step explanation:

The difference of the square of a number and 9 is equal to 8 times that number. Find the positive solution.

let x = a number

[tex]x^2-9=8x\\x^2-8x-9\\(x-9)(x+1)\\x-9 = 0\\x=9\\x+1=0\\x=-1[/tex]

taking only the positive solution, we get x = 9

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